Items tagged with dsolve dsolve Tagged Items Feed




eqn1 := ((diff(f4(r), r))*r-f4(r)*f1(r)+f4(r))/(f4(r)*r^2) = 0

((diff(f4(r), r))*r-f4(r)*f1(r)+f4(r))/(f4(r)*r^2) = 0


eqn4 := f4(r)*(r*(diff(f1(r), r))+f1(r)^2-f1(r))/(f1(r)^2*r^2) = 2*m*Dirac(r)*f4(r)/r^2

f4(r)*(r*(diff(f1(r), r))+f1(r)^2-f1(r))/(f1(r)^2*r^2) = 2*m*Dirac(r)*f4(r)/r^2


dsolve({eqn1, eqn4})

[{-(2*Dirac(r)*(diff(f4(r), r))^2*m*r^2+4*Dirac(r)*(diff(f4(r), r))*f4(r)*m*r+2*Dirac(r)*f4(r)^2*m-f4(r)*(diff(diff(f4(r), r), r))*r^2-2*(diff(f4(r), r))*r*f4(r))/f4(r) = 0}, {f1(r) = ((diff(f4(r), r))*r+f4(r))/f4(r)}]



When I try to solve this system of ODE, Maple does not factor out f4(r) in eqn4.  How do I get Maple to solve eqn4? So that I can get the correct result for f1(r) below:


dsolve((r*(diff(f1(r), r))+f1(r)^2-f1(r))/(f1(r)^2*r^2) = 2*m*Dirac(r)/r^2)

f1(r) = -r/(2*m*Heaviside(r)-_C1-r)





I Need eliminate u(t) in Matrix U
How can I do it directly from dsolve without using string tools?



Is it possible to solve DDE with dsolve?


Eq1 := diff(x(t), t) = 1-.1*x(t)-0.5e-3*x(t)*v(t)/(1+0.1e-5*v(t));

Eq2 := diff(y(t), t) = 0.5e-3*x(t-10)*v(t-10)/(1+0.1e-5*v(t-10))-.3*y(t)-y(t)*z(t);

Eq3 := diff(v(t), t) = 200*y(t-10)-8*v(t);

Eq4 := diff(z(t), t) = 2*y(t)*z(t)-.15*z(t);

ics := x(0) = 1, y(0) = 1, v(0) = 5, z(0) = 1;


I've got the following diff.eq

y'(x)=sin(x*y(x)) given y(0)=1 

and need to solve it numerically which is why I've used:


This code doesn't return a value though and in fact, ans3 is being displayed as a procedure

"ans3:=proc(x_rkf45) ... end proc"

I don't quite understand why and what I need to do to get the required numerical solution


restart; macro(x = eta); einf := 4; gm1 := 10; gm2 := 5; mf := .5; pr := 6.2; le := 10; nb := .2; nt := .2; r := 2; tr := 2; bi := .5; m := 2; tr1 := 1.5;
a1 := (m+1)*(1/2);
eqs1 := diff(f(x), [`$`(x, 3)])+a1*f(x)*(diff(f(x), [`$`(x, 2)]))-m*(diff(f(x), [`$`(xx, 2)]))^2+gm1*g(x)-gm2*h(x)-mf*(diff(f(x), [`$`(x, 1)])) = 0;
eqs2 := diff(g(x), [`$`(x, 2)])+a1*pr*f(x)*(diff(g(x), [`$`(x, 1)]))+pr*nb*(diff(g(x), [`$`(x, 1)]))*(diff(h(x), [`$`(x, 1)]))+pr*nt*(diff(g(x), [`$`(x, 1)]))^2+(4/3)*r1*(diff((1+(tr-1)*g(x))^3*(diff(g(x), [`$`(x, 1)])), x)) = 0;
eqs3 := diff(h(x), [`$`(x, 2)])+a1*le*f(x)*(diff(h(x), [`$`(x, 1)]))+nt*(diff(g(x), [`$`(x, 2)]))/nb = 0;
bcs1 := f(0) = 0, (D(f))(0) = 1, (D(f))(einf) = 0;
bcs2 := (D(g))(0) = bi*(g(0)-1), g(einf) = 0;
bcs3 := h(0) = 1, h(einf) = 0;
eqs := {bcs1, bcs2, bcs3, eqs1, eqs2, eqs3};
sol1 := dsolve(eqs, [f(x), g(x), h(x)], numeric, output = listprocedure);

If I typed the above line it's showing 

Error, (in dsolve/numeric/process_input) missing differential equations and initial or boundary conditions in the first argument: eqs

Kindly, I request you to do the needful as early as possible.

So I am trying to solve a given ODE using calculated christoffel symbols found by maple, and in order to get the correct christoffel symbols, I need my function to be r=x-x_s, where x is not a function of t. However, I then have to solve the ODE where x is a function of t. Maple used the r value to find the christoffel symbols which has x in it, and now I want to find the origonal function of x(t), but I can't have x and x(t) in the same ODE. If I change r=x-x_s to r=x(t)-x_s, I get the wrong christoffel symbols. How can I solve my ODE?

I try to solve a set of differential equations with boundary conditions by dsolve command but I got this error:


odes := D2*(diff(P(x), x))/((3*D1*a+4*D2)*P(x))-(diff(S(x), x))/(q*S(x)-1) = 0, diff(S(x), `$`(x, 2))+(diff(S(x), x))*cotx+4*pi*(3*D1*a+4*D1)*P(x)/((q*S(x)-1)*D2) = 0

ics := P((1/2)*pi) = 1, S((1/2)*pi) = -1, (D(S))((1/2)*pi) = 0, (D(P))((1/2)*pi) = 0

sol := dsolve({ics, odes}, numeric);
Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {x, (1/2)*pi}


Does any body knows what the problem is??



i want to solve the 2nd order ODE y''=0.8y'arctan(x)+xy    -2<x<1

the maple code used is:

>maplesol := dsolve({ (D(D(y)))(x) =0.8*arctan(x)*(D(y))(x)+x*y(x),y(-2)=1.3,D(y)(-2)=0.7});

and maple only gives out maplesol:=


I think its something to do with the arctan(x) because when i remove it, i get an answer.

Hi there,

I'm trying to get the values from the output of a dsolve command.

I have a system of differential equations:

de1 := diff(V(t), t) = V(t)-(1/3)*V(t)^3-W(t)+Ie;
de2 := diff(W(t), t) = 0.8e-1*(V(t)+.7-.8*W(t))

For a range of the independent variable t and for some given values of the parameter Ie, I would like to get the value of the dependent variable V, as well as its minimum/maximum values for each Ie.

Can anybody suggest a solution please?


This is the worksheet:




Hello friends;

I want to solve 3 - second orger equations with  6 unkowns. 

When i say just dsolve without boundry conditions it is solving but so complicated. 

_C6Ci  it is giving like that which i dont know the meaning of Ci.

But with boundry conditions it is not solving .

May you help me please where i am doing wrong. I downloaded the file.


How to numerically solve the problem

with Maple? Such type problems arise in elasticity theory (for example, see

Edit. Typo in the code:sin(y(x)) instead of sin(x).


I do not think the current API for dsolve when asking for series solution is done right. If one wants to obtain a series solution for an ODE, but wants different order than the default 6, now one must set this value using a global setting before making the call, like this:


It would be better if options to calls are passed along with the other parameters in the call itself. Something like


This should also apply to any command that takes Order, such as series(cos(x),x=0,order=10);

Passing options and values to functions using global and environment variables is not safe and not a good way to go about it as it can cause programming errors.

Hi I'm new to maple

I wanted to use dsolve to solve and equation but instead of getting an answer, maple returns an integration.

What could the promblem be?


I try to save results of numeric integration of ODE, returned by dsolve. I address very simple equation and before saving all works as needed:

S1 := dsolve([diff(z(x), x$2)+z(x) = -2, z(0)=0, z(1)=1], z(x), 'numeric', 'output' = listprocedure);

F1 := unapply(rhs(S1[2])(x), x); plot(F1, 0..1, thickness=3);

Next I save solution S1 by save operator:

save S1,  filename;

S1 saved and likely looks correctly:

S1 := [x = proc (x) local _res, _dat, _solnproc; option
`Copyright (c) 1993 by the University of Waterloo. All rights reserved.`; _dat
:= Array(1..4, {1 = proc (outpoint) local X, Y, YP, yout, errproc, L, V, i; ........................................................

Operator read reads S1 from file:
read filename;


F1 := unapply(rhs(S1[2])(x), x);

returns an error:

Error, (in unknown) invalid input: the 1st argument to pointto is not a valid pointer handle

How to save solution correctly?



I am trying to make c (0.001<=c<=0.02) a random value at each time step.But with my code c is choosing randomly from the interval then solveing the equation for fixed c at each time step.

How can I mack c a diffrent random value at each time step?

This is my code:

> with(DEtools); with(plots);
> Ra := RandomTools:-Generate(distribution(Uniform(0.001, 0.02))); c := Ra;
> f := .1;
> eq := diff(X(t), t) = 1-f-c*X(t);
> init := X(0) = 100;
> sol := dsolve({eq, init}, {X(t)}, range = 0 .. 100, numeric);
> odeplot(sol, [[t, X(t)]], t = 0 .. 100);


Thank you

1 2 3 4 5 6 7 Last Page 1 of 20